Preventive or therapeutic agent for fibrosis

ABSTRACT

Provided is siRNA effective for the treatment of fibrosis and a pharmaceutical containing the siRNA.

This application is a continuation application of U.S. Ser. No.13/842,080 filed Mar. 15, 2013, allowed, incorporated herein byreference, which was a National Stage of PCT/JP11/073628 filed Oct. 14,2011 and claims the benefit of JP 2010-231946 filed Oct. 14, 2010.

TECHNICAL FIELD

The present invention relates to a therapeutic agent for fibrosis.Specifically, the present invention relates to small interfering RNA(siRNA) targeting a gene encoding transforming growth factor (TGF)-β1and a pharmaceutical containing the siRNA.

BACKGROUND ART

Pulmonary fibrosis refers to a symptom in which lung tissues becomefibrotic due to the accumulation of excess collagen and otherextracellular matrix. Within a classification of pulmonary fibrosis,idiopathic pulmonary fibrosis is a chronic intractable disease, carryinga poor prognosis with an average median survival time of three years anda five year survival rate of 20 to 40%. For the treatment of pulmonaryfibrosis, steroid drugs and immunosuppressants are used; however, noeffective therapy which can improve the prognosis is currentlyavailable, and thus development of a new therapeutic drug is demanded.

Recently, it has been revealed that there are many diseases whose onsetis attributed to a gene, and many genes are also reported to be involvedin pulmonary fibrosis (Patent Documents 1 to 4, Non Patent Documents 1to 6). As the main factor associated with pulmonary fibrosis, TGF-β1(Patent Documents 1 and 2, Non Patent Documents 2 to 6), Smad3 (NonPatent Document 1), MCP-1 (Patent Document 3), and the like arereported.

Meanwhile, a nucleic acid, particularly, siRNA induces degradation ofmRNA of a gene having a sequence identical or almost identical to aspecific sequence present in a cell, thereby inhibiting the expressionof a target gene (RNA interference). Accordingly, the function ofinhibiting the expression of the target gene because of RNA interferenceis useful for the amelioration or treatment of disease symptoms inducedby abnormal expression of a specific gene or a group of genes. As to thepulmonary fibrosis-associated genes as well, there are reports thatinhibition of the expression of those genes with siRNA was attempted(Patent Documents 1 to 4, Non Patent Documents 1 to 6).

However, the technologies reported to date have only exhibitedinhibitory effect of an siRNA sequence on a disease-associated gene inexperimental animals (mice and rats), while they have not sufficientlyexhibited effects specifically on human genes. Further, concerning theinhibitory effect of siRNA, while the effects of siRNA at concentrationsof 200 nM (Non Patent Document 1) and 20 to 500 nM (Non Patent Document5) are exhibited, a nucleic acid molecule capable of inhibiting theexpression of a pulmonary fibrosis-associated gene efficiently at a lowconcentration is not demonstrated.

Several tens of siRNAs targeting the TGF-β1 gene have been reported sofar (Patent Documents 1 and 5 to 7). However, considering that thefull-length TGF-β1 gene consists of 2346 bases (GenBank Accession No.NM_(—)000660.3) and there are countless possible combinations ofselecting an approximately 20-mer sequence out of the full-length gene,it is not easy to design an dsRNA or siRNA molecule capable of moreefficiently inhibiting the expression of the gene from the combinations.

RELATED ART DOCUMENTS Patent Documents

-   [Patent Document 1] WO2007/109097-   [Patent Document 2] WO2003/035083-   [Patent Document 3] JP-A-2007-119396-   [Patent Document 4] JP-A-2009-516517-   [Patent Document 5] WO2009/061417-   [Patent Document 6] WO2008/109548-   [Patent Document 7] W02007/79224

Non Patent Documents

-   [Non Patent Document 1] Wang Z, Gao Z, Shi Y, Sun Y, Lin Z, Jiang H,    Hou T, Wang Q, Yuan X, Zhu X, Wu H, Jin Y, J Plast Reconstr Aesthet    Surg, 1193-1199, 60, 2007-   [Non Patent Document 2] Hwang M, Kim H J, Noh H J, Chang Y C, Chae Y    M, Kim K H, Jeon J P, Lee T S, Oh H K, Lee Y S, Park K K, Exp Mol    Pathol, 48-54, 81, 2006-   [Non Patent Document 3] Takabatake Y, Isaka Y, Mizui M, Kawachi H,    Shimizu F, Ito T, Hori M, Imai E, Gene Ther, 965-973, 12, 2005-   [Non Patent Document 4] Xu W, Wang L W, Shi J Z, Gong Z J,    Hepatobiliary Pancreat Dis Int, 300-308, 8, 2009-   [Non Patent Document 5] Liu X J, Ruan C M, Gong X F, Li X Z, Wang H    L, Wang M W, Yin J Q, Biotechnol Lett, 1609-1615, 27, 2005-   [Non Patent Document 6] Jutaro Fukumoto, Saiko Suetsugu, Chika    Harada, Tomonobu Kawaguchi, Naoki Hamada, Takashige Maeyama,    Kazuyoshi Kuwano, and Yoichi Nakanishi, The Journal of The Japanese    Respiratory Society, 185, 46, 2008

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

The present invention relates to provision of siRNA effective for thetreatment of fibrosis and a pharmaceutical containing the siRNA.

Means for Solving the Problem

The present inventors have conducted intensive research to solve theaforementioned problem. As a result, they have found that specific siRNAtargeting the human TGF-β1 gene can effectively inhibit the TGF-β1expression in human cells, and further, improve the symptoms ofpulmonary fibrosis in the lungs of a mouse model of pulmonary fibrosiswithout inducing the interferon reaction.

That is, the present invention relates to the following 1) to 19).

1) An siRNA having a full length of 30 or fewer nucleotides andtargeting a sequence comprising 17 to 23 consecutive bases selected fromthe group consisting of bases at positions 1285 to 1318, bases atpositions 1398 to 1418, bases at positions 1434 to 1463, bases atpositions 1548 to 1579, bases at positions 1608 to 1628, bases atpositions 1700 to 1726, bases at positions 1778 to 1798, bases atpositions 1806 to 1826, and bases at positions 1887 to 1907 of SEQ IDNO: 1.

2) The siRNA according to the aforementioned 1), which is selected fromthe following (a) to (s):

(a) an siRNA comprising a sense sequence of SEQ ID NO: 2 and anantisense sequence of SEQ ID NO: 3;

(b) an siRNA comprising a sense sequence of SEQ ID NO: 4 and anantisense sequence of SEQ ID NO: 5;

(c) an siRNA comprising a sense sequence of SEQ ID NO: 6 and anantisense sequence of SEQ ID NO: 7;

(d) an siRNA comprising a sense sequence of SEQ ID NO: 8 and anantisense sequence of SEQ ID NO: 9;

(e) an siRNA comprising a sense sequence of SEQ ID NO: 10 and anantisense sequence of SEQ ID NO: 11;

(f) an siRNA comprising a sense sequence of SEQ ID NO: 12 and anantisense sequence of SEQ ID NO: 13;

(g) an siRNA comprising a sense sequence of SEQ ID NO: 14 and anantisense sequence of SEQ ID NO: 15;

(h) an siRNA comprising a sense sequence of SEQ ID NO: 16 and anantisense sequence of SEQ ID NO: 17;

(i) an siRNA comprising a sense sequence of SEQ ID NO: 18 and anantisense sequence of SEQ ID NO: 19;

(j) an siRNA comprising a sense sequence of SEQ ID NO: 20 and anantisense sequence of SEQ ID NO: 21;

(k) an siRNA comprising a sense sequence of SEQ ID NO: 22 and anantisense sequence of SEQ ID NO: 23;

(l) an siRNA comprising a sense sequence of SEQ ID NO: 24 and anantisense sequence of SEQ ID NO: 25;

(m) an siRNA comprising a sense sequence of SEQ ID NO: 26 and anantisense sequence of SEQ ID NO: 27;

(n) an siRNA comprising a sense sequence of SEQ ID NO: 28 and anantisense sequence of SEQ ID NO: 29;

(o) an siRNA comprising a sense sequence of SEQ ID NO: 30 and anantisense sequence of SEQ ID NO: 31;

(p) an siRNA comprising a sense sequence of SEQ ID NO: 32 and anantisense sequence of SEQ ID NO: 33;

(q) an siRNA comprising a sense sequence of SEQ ID NO: 34 and anantisense sequence of SEQ ID NO: 35;

(r) an siRNA comprising a sense sequence of SEQ ID NO: 36 and anantisense sequence of SEQ ID NO: 37; and

(s) an siRNA comprising a sense sequence of SEQ ID NO: 54 and anantisense sequence of SEQ ID NO: 55.

3) The siRNA according to the aforementioned 1) or 2), wherein 1 to 10consecutive nucleotides excluding an overhang nucleotide from the 3′terminus of the sense strand of the siRNA are converted into DNA.

4) The siRNA according to the aforementioned 1) to 3), wherein 1 to 10consecutive nucleotides from the 5′ terminus of the antisense strand ofthe siRNA are converted into DNA.

5) The siRNA according to the aforementioned 1) to 4), wherein 1 to 10consecutive nucleotides excluding an overhang nucleotide from the 3′terminus of the sense strand of the siRNA are converted into DNA and 1to 10 consecutive nucleotides from the 5′ terminus of the antisensestrand of the siRNA are converted into DNA.

6) The siRNA according to the aforementioned 1) to 5), wherein the 5′terminus of the antisense strand is monophosphorylated ormonothiophosphorylated.

7) A pharmaceutical composition containing the siRNA according to any ofthe aforementioned 1) to 6).

8) A TGF-β1 gene expression inhibitor containing the siRNA according toany of the aforementioned 1) to 6) as an active ingredient.

9) A preventive or therapeutic agent for fibrosis containing the siRNAaccording to any of the aforementioned 1) to 6) as an active ingredient.

10) A preventive or therapeutic agent for pulmonary fibrosis or lungcancer containing the siRNA according to any of the aforementioned 1) to6) as an active ingredient.

11) Use of the siRNA according to the aforementioned 1) to 6) for theproduction of a TGF-β1 gene expression inhibitor.

12) Use of the siRNA according to the aforementioned 1) to 6) for theproduction of a preventive or therapeutic agent for fibrosis.

13) Use of the siRNA according to the aforementioned 1) to 6) for theproduction of a preventive or therapeutic agent for pulmonary fibrosisor lung cancer.

14) The siRNA according to the aforementioned 1) to 6) for use ininhibiting TGF-β1 gene expression.

15) The siRNA according to the aforementioned 1) to 6) for use inpreventing or treating fibrosis.

16) The siRNA according to the aforementioned 1) to 6) for use inpreventing or treating pulmonary fibrosis or lung cancer.

17) A method for inhibiting TGF-β1 gene expression, comprisingadministering the siRNA according to the aforementioned 1) to 6) to ahuman or animal.

18) A method for preventing or treating fibrosis, comprisingadministering the siRNA according to the aforementioned 1) to 6) to ahuman or animal.

19) A method for preventing or treating pulmonary fibrosis or lungcancer, comprising administering the siRNA according to theaforementioned 1) to 6) to a human or animal.

Effects of the Invention

Since the siRNA of the present invention can efficiently suppress orinhibit the TGF-β1 expression at a low concentration, it is useful as apharmaceutical for preventing or treating fibrosis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the rate of inhibition of the expression ofTGF-β1 mRNA by siRNA;

FIG. 2 is a graph showing the rate of inhibition of the expression ofTGF-β1 mRNA by chimeric siRNA;

FIG. 3 is a graph showing the rate of inhibition of the expression ofTGF-β1 mRNA by phosphate- or thiophosphate-linked chimeric siRNA;

FIG. 4 is a graph showing the rate of inhibition of the TGF-β1expression in a pulmonary fibrosis model; and

FIG. 5 is an optical microscopic picture of lung tissue sections (H.E.staining and Masson's trichrome staining) (magnification: 5×).

MODE FOR CARRYING OUT THE INVENTION

The sequence targeted by the siRNA of the present invention consists of17 to 23 consecutive bases selected from the group consisting of basesat positions 1285 to 1318, bases at positions 1398 to 1418, bases atpositions 1434 to 1463, bases at positions 1548 to 1579, bases atpositions 1608 to 1628, bases at positions 1700 to 1726, bases atpositions 1778 to 1798, bases at positions 1806 to 1826, and bases atpositions 1887 to 1907 of SEQ ID NO: 1. Here, the 17 to 23 consecutivebases selected from each group are preferably 19 to 23 bases, and morepreferably 21 bases.

The base sequence of SEQ ID NO: 1 represents the base sequence of TGF-β1mRNA, and this sequence information is registered with GenBank under theGenBank Accession No. NM_(—)000660.3.

The siRNA of the present invention is formed by hybridization of anantisense strand, which has a sequence complementary to theaforementioned target sequence of TGF-β1 mRNA, and a sense strand, whichhas a sequence complementary to this antisense strand. The siRNA of thepresent invention has a cleaving activity on TGF-β1 mRNA (i.e., RNAinterference action) and an ability to inhibit the translation of thismRNA, namely, an ability to inhibit the expression of the TGF-β1 gene.

Regarding the nucleotide length of the siRNA of the present invention,the lengths of the sense strand and the antisense strand may be the sameor different, and the full-length siRNA consists of 30 or fewernucleotides, preferably 25 or fewer nucleotides, more preferably 23 orfewer nucleotides, or 21 nucleotides.

Further, both ends of the sense and antisense strands may be blunt endsor the 3′ terminus of each strand may have an overhang (i.e., cohesiveend). Here, the “blunt end” refers to a configuration in which, in theterminal region of double-stranded RNA, the terminal region of the sensestrand and the corresponding terminal region of the antisense strand arepaired up without forming a stretch of single strand. Further, the“overhang,” also called a dangling end, refers to a configuration inwhich double-stranded RNA fails to form a double strand in the terminalregion of the sense strand or the corresponding terminal region of theantisense strand due to the missing of a pairing base, generating astretch of single strand (cohesive end).

As to the number of bases in the cohesive end portion, it consists of 1to 10 nucleotides, preferably 1 to 4 nucleotides, and more preferably 1to 2 nucleotides. It should be noted that there is no association in thelength of the cohesive end between the two strands, and the two strandsmay each have a different length. The nucleotide in the cohesive endportion may be either RNA or DNA, and although it is preferably a basecomplementary to the target TGF-β1 mRNA, it may be a non-complementarybase as long as the siRNA of the present invention retains theaforementioned RNA interference ability.

The siRNA of the present invention may be one double-stranded RNAcomposed of two separate strands. Besides that, it may also be a singlestrand RNA forming a double-stranded RNA through formation of astem-loop structure. That is, the siRNA of the present invention alsoincludes RNA forming a loop composed of 2 to 4 nucleotides at the 5′terminus of the sense strand and the 3′ terminus of the antisense strandand RNA forming a loop composed of 2 to 4 nucleotides at the 3′ terminusof the sense strand and the 5′ terminus of the antisense strand.Further, it also includes RNA forming loops composed of 2 to 4nucleotides at the 5′ terminus of the sense strand and the 3′ terminusof the antisense strand as well as the 3′ terminus of the sense strandand the 5′ terminus of the antisense strand.

The siRNA of the present invention and the target sequence arepreferably identical; however, they may be substantially identical,i.e., have homologous sequences, as long as the siRNA can induce theaforementioned RNA interference. Specifically, as long as the sequenceof the antisense strand of the siRNA of the present invention hybridizeswith the target sequence, one or several (for example, two, three, andfour) mismatches may be present. That is, the siRNA of the presentinvention includes siRNA having a sequence modified with thesubstitution, addition, or deletion of one or several bases relative tothe target sequence and capable of inducing RNA interference, or siRNAhaving 85% or more, preferably 90% or more, preferably 95% or more, andmore preferably 98% or more sequence identity to the target sequence andcapable of inducing RNA interference.

It is to be noted that the hybridization conditions used herein refersto, when using the siRNA of the present invention as a pharmaceutical byadministering it to the living body, the conditions in the living body,and when using the siRNA of the present invention as a reagent in vitro,moderately or highly stringent conditions. Examples of such conditionsinclude hybridization conditions of 400 mM NaCl, 40 mM PIPES, pH 6.4, 1mM EDTA, and a hybridization time of 12 to 160 hours at 50° C. to 70° C.These conditions are well known to those skilled in the art anddescribed by Sambrook et al. (Molecular Cloning: A Laboratory Manualsecond edition, Cold Spring Harbor Laboratory Press, New York, USA,1989).

Also, the sequence identity may be calculated by Lipman-Pearson method(Science, 227, 1435, (1985)), etc., and for example, it is calculated byusing Search homology program of genetic information processing softwareGenetyx-Win (Ver.5.1.1; Software Development Co., Ltd.) with settingUnit size to compare (ktup) at 2.

Also, the siRNA of the present invention includes siRNA in which thenucleotides of either the sense strand or the antisense strand areentirely converted into DNA (hybrid siRNA) and siRNA in which thenucleotides of the sense and/or antisense strand are partially convertedinto DNA (chimeric siRNA), as long as the siRNA can induce theaforementioned RNA interference.

Herein, conversion of RNA nucleotide into DNA means conversion of AMPinto dAMP, GMP into dGMP, CMP into dCMP, and UMP into dTMP.

As the hybrid siRNA, one in which the nucleotides of the sense strandare converted into DNA is preferable. Examples of the chimeric siRNAinclude one in which the nucleotides in the downstream side (i.e., the3′ terminal side of the sense strand and the 5′ terminal side of theantisense strand) are partially converted into DNA. Specific examplesthereof include one in which the nucleotides in the 3′ terminal side ofthe sense strand and the 5′ terminal side of the antisense strand areboth converted into DNA and one in which the nucleotides of either the3′ terminal side of the sense strand or the 5′ terminal side of theantisense strand are converted into DNA. Also, the length of thenucleotide to be converted is preferably any length up to be equivalentto ½ of the RNA molecule or shorter, for example, 1 to 13 nucleotides,preferably 1 to 10 nucleotides from the terminus. From the viewpoints ofthe RNA interference effect, and the stability, safety, etc. of the RNAmolecule, examples of favorable chimeric siRNA include one in which thetwo strands each have a nucleotide length of 19 to 23, and 1 to 10,preferably 1 to 8, and more preferably 1 to 6 nucleotides excluding anoverhang nucleotide(s) from the 3′ terminus of the sense strand and 1 to10, preferably 1 to 8, and more preferably 1 to 6 nucleotides from the5′ terminus of the antisense strand are consecutively converted into DNAin an arbitrary number (see [Table 2] to be shown below). Also, in thiscase, it is more preferable that the numbers of DNA converted in thesense strand (excluding a overhang nucleotide(s)) and the antisensestrand be the same.

Also, the siRNA of the present invention may be one in which thenucleotide (i.e., ribonucleotide and deoxyribonucleotide) is anucleotide analog having chemically modified sugar, base, and/orphosphate, as long as the siRNA can induce the aforementioned RNAinterference. Examples of the nucleotide analog having a modified baseinclude 5-position-modified uridine or cytidine (for example,5-propynyluridine, 5-propynylcytidine, 5-methylcytidine,5-methyluridine, 5-(2-amino)propyluridine, 5-halocytidine,5-halouridine, and 5-methyloxyuridine); 8-position-modified adenosine orguanosine (for example, 8-bromoguanosine); deazanucleotide (for example,7-deaza-adenosine); and O- and N-alkylated nucleotide (for example,N6-methyladenosine).

Also, examples of the nucleotide analog having a modified sugar includea 2′-position sugar modified analog, in which 2′-OH of theribonucleotide is replaced by H, OR, R, a halogen atom, SH, SR, NH₂,NHR, NR₂, CN (wherein, R represents an alkyl, alkenyl, or alkynyl grouphaving 1 to 6 carbon atoms), and the like, a 5′-terminal phosphorylatedanalog or a 5′-terminal monothiophosphorylated analog, in which the 5′terminal OH group is monophosphorylated or monothiophosphorylated.

Examples of the nucleotide analog having a modified phosphate includeone in which a phosphoester group linking adjacent ribonucleotides isreplaced by a phosphothioate group.

Also, aside from the aforementioned nucleotide analogs, the siRNA of thepresent invention may have a specific substituent or functional moleculebound to at least one of the first to sixth nucleotides from the 5′terminus or the 3′ terminus of the sense strand (5′ terminus, 3′terminus, or an internal base or sugar other than the terminus) directlyor via a linker, and the substituent or functional molecule ispreferably bound to at least one of the first to sixth, preferably thefirst to fourth nucleotides from the 5′ terminus of the sense strand.

Here, examples of the substituent include an amino group; a mercaptogroup; a nitro group; an alkyl group having 1 to 40 (preferably 2 to 20,more preferably 4 to 12) carbon atoms; an aminoalkyl group having 1 to40 (preferably 2 to 20, more preferably 4 to 12) carbon atoms; athioalkyl group having 1 to 40 (preferably 2 to 20, more preferably 4 to12) carbon atoms; an alkoxyl group having 1 to 40 (preferably 2 to 20,more preferably 4 to 12) carbon atoms; an aminoalkoxyl group having 1 to40 (preferably 2 to 20, more preferably 4 to 12) carbon atoms; athioalkoxyl group having 1 to 40 (preferably 2 to 20, more preferably 4to 12) carbon atoms; a mono- or di-alkyl amino group having 1 to 40(preferably 2 to 20, more preferably 4 to 12) carbon atoms; an alkylthiogroup having 1 to 40 (preferably 2 to 20, more preferably 4 to 12)carbon atoms; a polyethylene oxide group having 2 to 40 (preferably 2 to20, more preferably 4 to 12) carbon atoms; and a polypropylene oxidegroup having 3 to 39 (preferably 3 to 21, more preferably 3 to 12)carbon atoms. The RNA interference effect can be remarkably enhanced bybinding these substituents.

Examples of the functional molecule include sugar, protein, peptide,amino acid, DNA, RNA (including tRNA), aptamers, modified nucleotides,low molecular weight organic and inorganic materials, cholesterol,dendrimers, lipid, and polymer materials. Through addition of thesefunctional molecules, the siRNA of the present invention can attainexcellent RNA interference effect and beneficial effect attributed tothe functional molecules.

Examples of the aforementioned sugar include monosaccharides such asglucose, galactose, glucosamine, and galactosamine, and oligosaccharidesor polysaccharides formed by an arbitrary combination of thesemonosaccharides.

As the aforementioned protein, proteins present inside the living body,proteins having pharmacological actions, proteins having molecularrecognition actions, and the like can be used, and examples of theseproteins include importin-β protein, avidin, and antibodies.

Specific examples of the aforementioned DNA include DNA of 5 to 50 basesin length, preferably 5 to 25 bases in length.

Examples of the aforementioned peptide include octa-arginine peptide R8,a nuclear localization signal peptide sequence (such as HIV-1 Tat andSV40T antigen), a nuclear export signal peptide (such as HIV-1 Rev andMAPKK), and a membrane fusion peptide. Examples of the aforementionedmodified nucleotide include one having a modified phosphate skeletonsuch as phosphorothioate or boranophosphate DNA/RNA; a 2′-modifiednucleotide such as 2′-OMe modified RNA and 2′-F modified RNA; a modifiednucleotide in which the sugar molecules are cross-linked such as LNA(i.e., Locked Nucleic Acid) and ENA (i.e., 2′-O,4′-C-ethylene-bridgednucleic acids); and a modified nucleotide having a different basicskeleton such as PNA (i.e., peptide nucleic acid) andmorpholino-nucleotide (see WO2008/140126 and WO2009/123185).

Examples of the aforementioned low molecular weight organic andinorganic materials include fluorescent materials such as Cy3 and Cy5;biotin; quantum dot; and fine gold particles. Examples of theaforementioned dendrimers include poly(amidoamine) dendrimer. Examplesof the aforementioned lipid include, in addition to linoleic acid,1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), etc.,double-stranded lipid having two hydrophobic groups as described inWO2009/123185. Examples of the aforementioned polymer materials includepolyethylene glycol and polyethylene imine.

Here, the group having a functional molecule may be the functionalmolecule residue per se, or a functional molecule residue to which oneof the functional groups of a bifunctional linker is bound. That is, inthe former case, the functional molecule is directly bound to a certainpart of the aforementioned sense strand RNA, and in the latter case, thefunctional molecule is bound to a certain part of the aforementionedsense strand RNA via a bifunctional linker. Herein, no particularlimitation is imposed on the bifunctional linker as long as it is alinker having two functional groups, and for example, N-succinimidyl3-(2-pyridyldithio) propionate, N-4-maleimidobutyric acid,S-(2-pyridyldithio) cysteamine, iodoacetoxysuccinimide,N-(4-maleimidobutyryloxy)succinimide,N-[5-(3′-maleimidopropylamido)-1-carboxypentyl]iminodiacetic acid,N-(5-aminopentyl)-iminodiacetic acid, and the like can be used.

Although no particular limitation is imposed on the binding site on theaforementioned sense strand RNA for a substituent, a functionalmolecule, or a linker connecting the substituent or functional molecule,they are preferably bound in such a way that they substitute a hydrogenatom constituting a hydroxyl group in the phosphate moiety of a certainnucleotide in the sense strand RNA.

The siRNA of the present invention is specifically exemplified bydouble-stranded RNA containing the sense sequences and the antisensesequences of (a) to (s) below.

TABLE 1 SEQ SEQ siRNA Target site ID ID No. base positions Sense (5′→3′)NO Anti-sense (5′→3′) NO (a) 1285~1305 CCGAGAAGCGGUACCUGAACC  2UUCAGGUACCGCUUCUCGGAG  3 (b) 1298~1318 CCUGAACCCGUGUUGCUCUCC  4AGAGCAACACGGGUUCAGGUA  5 (c) 1398~1418 CCUGGCGAUACCUCAGCAACC  6UUGCUGAGGUAUCGCCAGGAA  7 (d) 1434~1454 GCGACUCGCCAGAGUGGUUAU  8AACCACUCUGGCGAGUCGCUG  9 (e) 1435~1455 CGACUCGCCAGAGUGGUUAUC 10UAACCACUCUGGCGAGUCGCU 11 (f) 1436~1456 GACUCGCCAGAGUGGUUAUCU 12AUAACCACUCUGGCGAGUCGC 13 (g) 1438~1458 CUCGCCAGAGUGGUUAUCUUU 14AGAUAACCACUCUGGCGAGUC 15 (h) 1440~1460 CGCCAGAGUGGUUAUCUUUUG 16AAAGAUAACCACUCUGGCGAG 17 (i) 1441~1461 GCCAGAGUGGUUAUCUUUUGA 18AAAAGAUAACCACUCUGGCGA 19 (j) 1443~1463 CAGAGUGGUUAUCUUUUGAUG 20UCAAAAGAUAACCACUCUGGC 21 (k) 1548~1568 GGGAUAACACACUGCAAGUGG 22ACUUGCAGUGUGUUAUCCCUG 23 (l) 1557~1577 CACUGCAAGUGGACAUCAACG 24UUGAUGUCCACUUGCAGUGUG 25 (s) 1557~1579 CACACUGCAAGUGGACAUCAACG 54CGUUGAUGUCCACUUGCAGUGUG 55 (m) 1608~1628 CCACCAUUCAUGGCAUGAACC 26UUCAUGCCAUGAAUGGUGGCC 27 (n) 1700~1720 GCCCUGGACACCAACUAUUGC 28AAUAGUUGGUGUCCAGGGCUC 29 (o) 1706~1726 GACACCAACUAUUGCUUCAGC 30UGAAGCAAUAGUUGGUGUCCA 31 (p) 1778~1798 GACCUCGGCUGGAAGUGGAUC 32UCCACUUCCAGCCGAGGUCCU 33 (q) 1806~1826 CCAAGGGCUACCAUGCCAACU 34UUGGCAUGGUAGCCCUUGGGC 35 (r) 1887~1907 CCCUGUACAACCAGCAUAACC 36UUAUGCUGGUUGUACAGGGCC 37

Also, preferred examples of the chimeric siRNA include one in which 1 to8 nucleotides from the 3′ terminus of the sense strand and 1 to 6nucleotides from the 5′ terminus of the antisense strand areconsecutively converted into DNA in an arbitrary number. Examples of thepreferred chimeric siRNA obtained using the aforementioned siRNA (1) areas follows.

TABLE 2 SEQ SEQ SiRNA ID ID No. Sense (5′ → 3′) NO Anti-sense (5′ → 3′)NO (I-C8a) CACUGCAAGUGGAcatcaacg 38 ttgatgUCCACUUGCAGUGUG 39 (I-C7)CACUGCAAGUGGACatcaacg 40 ttgatGUCCACUUGCAGUGUG 41 (I-C6)CACUGCAAGUGGACAtcaacg 42 ttgaUGUCCACUUGCAGUGUG 43 (I-C5)CACUGCAAGUGGACAUcaacg 44 ttgAUGUCCACUUGCAGUGUG 45 (I-C4a)CACUGCAAGUGGACAUCaacg 46 ttGAUGUCCACUUGCAGUGUG 47 (I-C3)CACUGCAAGUGGACAUCAacg 48 tUGAUGUCCACUUGCAGUGUG 49 (I-C2)CACUGCAAGUGGACAUCAAcg 50 UUGAUGUCCACUUGCAGUGUG 25 (I-C1)CACUGCAAGUGGACAUCAACg 51 UUGAUGUCCACUUGCAGUGUG 25 (I-C4b)CACUGCAAGUGGACAUCaacg 46 UUGAUGUCCACUU0CAGUGtg 56In the table, capital letters, small letters, and underlines indicateRNA, DNA, and overhang positions, respectively.

Although no particular limitation is imposed on the production method ofthe siRNA of the present invention, it can be synthesized by a knownproduction method, for example, in vitro chemical synthesis andtranscriptional synthesis using promoters and RNA polymerases.

Chemical synthesis can be performed by a nucleic acid synthesizer, usingan amidite resin containing nucleic acid molecules, which are theconstituent element of siRNA, as the raw material.

Transcriptional synthesis can be performed by in vitro transcription,which enables synthesis of double-stranded RNA by trimming hairpin RNA.

The siRNA of the present invention thus obtained can effectively inhibitthe TGF-β1 expression in human alveolar epithelium-derived cells at themRNA level, and further, exhibit an improving effect on the symptoms ofpulmonary fibrosis in the lungs of a mouse model of pulmonary fibrosiswithout inducing the interferon reaction, as will be demonstrated laterin Examples.

Accordingly, the siRNA of the present invention and an expression vectorcapable of expressing the siRNA in subjects administered with the vectorare useful as a pharmaceutical for administration to a human or animal(pharmaceutical composition). Specifically, a pharmaceutical for theinhibition of the TGF-β1 gene expression, a pharmaceutical forpreventing or treating a disease attributable to overexpression ofTGF-β1 such as fibrosis, namely, a preventive or therapeutic agent forfibrosis.

Here, there is a variety of diseases that lead to fibril formation inthe lungs, such as interstitial pneumonia, cystic fibrosis, chronicobstructive pulmonary disease (COPD), acute respiratory distresssyndrome (ARDS), inflammatory lung disease, pulmonary infection,radiation pneumonitis, drug-induced interstitial pneumonia, and collagendisease-associated interstitial pneumonia; however, among idiopathicinterstitial pneumonias (IIPs) of unidentified cause, idiopathicpulmonary fibrosis (IPF) is particularly preferable. As theclinicopathologic disease, IIPs include idiopathic pulmonary fibrosis(IPF), non-specific interstitial pneumonia (NSIP), cryptogenicorganizing pneumonia (COP/BOOP), acute interstitial pneumonia (AIP),desquamative interstitial pneumonia (DIP), respiratorybronchiolitis-associated interstitial pneumonia (RB-ILD), lymphocyticinterstitial pneumonia (LIP), and the like.

In addition, there are reports that TGF-β1 promotes cancer, inparticular lung adenocarcinoma invasion and metastasis (Mol Cell Biochem(2011) 355:309-314, Cancer Genomics Proteomics 2010, 7, 217), TGF-β1 isoverexpressed at sites of normal tissue injury after cancer therapy andthe normal tissue injury can be prevented by targeting the TGF-β1pathway (The oncologist 2010; 15: 350-359), etc. Accordingly, the siRNAof the present invention and an expression vector capable of expressingthe siRNA in subjects administered with the vector are useful as apharmaceutical for preventing or treating cancer, in particular lungcancer.

When using the siRNA of the present invention as a pharmaceutical,although it can be used as it is, it may also be allowed to form acomplex with highly branched cyclic dextrin or cycloamylose. Here,highly branched cyclic dextrin refers to glucan with a degree ofpolymerization of 50 to 5000 having an inner branched cyclic structuremoiety and an outer branched structure moiety, being produced byallowing branching enzymes to act on amylopectin. Here, the innerbranched cyclic structure moiety refers to a cyclic structure moietyformed by an α-1,4-glucoside bond and an α-1,6-glucoside bond, and theouter branched structure moiety refers to a non-cyclic structure moietybound to the inner branched cyclic structure moiety. Examples ofpreferred embodiments of the highly branched cyclic dextrin include onein which the degree of polymerization of the inner branched cyclicstructure moiety of the aforementioned glucan is 10 to 100, one in whichthe degree of polymerization of the outer branched structure moiety ofthe aforementioned glucan is 40 or higher, and one in which an averagedegree of polymerization of each unit chain of the aforementioned outerbranched structure moiety is 10 to 20. Also, highly branched cyclicdextrin is commercially available, and those commercial products canalso be used for the present invention.

Cycloamylose is cyclic α-1,4-glucan, in which glucose units are linkedby an α-1,4 linkage, and has a three-dimensional, deep hollow spacewithin the helix structure. Although no particular limitation is imposedon the degree of polymerization of glucose in cycloamylose used for thepresent invention, for example, it is 10 to 500, preferably 10 to 100,and more preferably 22 to 50. Cycloamylose can be prepared from glucoseusing enzymes such as amylomaltase. Also, cycloamylose is commerciallyavailable, and those commercial products can also be used for thepresent invention (see W02009/61003).

The siRNA of the present invention can be prepared as a pharmaceuticalcomposition using one or more pharmaceutically acceptable carriers ordiluents by an ordinary method. The pharmaceutical composition may begiven via any administration route such as pulmonary administration,nasal administration, oral administration, rectal administration, andinjection, and the administration may be systemic or local. The dosageform of the pharmaceutical composition may be any form suitable for useaccording to an administration route, such as a liquid, a suspension, anemulsion, a tablet, a pill, a pellet, a capsule, a powder, asustained-release preparation, a suppository, an aerosol, and a spray.

For example, in nasal administration, the active ingredient is dissolvedin an appropriate solvent (such as physiological saline and alcohol) andthe resulting solution is injected or added dropwise to the nose,whereby the active ingredient can be delivered. Alternatively, inpulmonary administration or nasal administration, the active ingredientis sprayed with an aerosol from a pressurized pack or a nebulizer usingan appropriate propellant such as dichlorodifluoromethane,trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide, orother appropriate gases, whereby the active ingredient can beconveniently delivered. When using pressurized aerosol, the dosage unitcan be fixed by providing a valve so that a measured amount isdelivered. Further, the active ingredient can also be administered as apowder inhalant.

In the case of injections, for example, the active ingredient can beformulated as a solution for parenteral administration to be given by abolus injection or continuous infusion (i.e., intravenous orintramuscular administration), and it is preferably formulated as aphysiologically compatible buffer such as Hanks' solution, Ringer'ssolution, and physiological saline. This solution may contain medicinalagents which are allowed to be added such as suspending agents,stabilizers, and/or dispersants. Alternatively, the active ingredientcan be prepared as a powder so that it is reconstructed with anappropriate diluent such as sterilized water not containing thermogenicsubstances before use. An injection preparation can be provided as, forexample, a unit dosage form in an ampoule or a multi-dose container withpreservatives.

For oral administration, the therapeutic agent of the present inventioncan be in the form of, for example, a tablet, a granule, a powder, anemulsion, a capsule, a syrup, an aqueous or oily suspension, or anelixir. In the case of a tablet or a pill, the composition can be coatedin order to delay dispersion and absorption in the gastrointestinaltract so that a long-lasting action is obtained.

Although no limitation is imposed on the pharmaceutically acceptablecarrier or diluent, examples thereof include liquids (such as water,oil, physiological saline, an aqueous solution of dextrose, and ethanol)and solids (such as acacia gum, gelatin, starch, glucose, lactose,sucrose, talc, sodium stearate, glycerol monostearate, keratin,colloidal silica, dried skim milk, and glycerol). Also, the therapeuticagent of the present invention may contain an appropriate agent which isadded to ordinary pharmaceutical compositions such as an aid, anantiseptic, a stabilizer, a thickening agent, a lubricant, a colorant, awetting agent, an emulsifier, and a pH buffer.

The pharmaceutical composition of the present invention can contain thesiRNA of the present invention in an amount of 0.001 to 50 mass %,preferably 0.01 to 10 mass %, and more preferably 0.1 to 1 mass %.

Although the dose of the pharmaceutical composition of the presentinvention is not particularly limited as long as the effective amount isapplied, for example, it is preferably 0.0001 to 100 mg, and morepreferably 0.002 to 1 mg per kg body weight.

For the pharmaceutical composition of the present invention, in place ofthe siRNA of the present invention, an expression vector capable ofexpressing the siRNA in a subject administered with the vector can alsobe used.

In this case, the expression vector can be constructed by, for example,inserting DNA capable of encoding the siRNA of the present inventioninto an appropriate vector used for gene therapy such as an adenovirusvector, an adeno-associated virus vector (AAV), or a lentivirus vector.

EXAMPLES

Hereinbelow, the present invention will be described in more detail withreference to Examples. However, the technical scope of the presentinvention is not limited to these Examples.

Example 1 Production of siRNA

The siRNA molecules targeting the TGF-β1 gene as shown in Table 3 belowwere designed and each siRNA oligonucleotide was chemically synthesized.The resulting oligonucleotides were purified by HPLC before use.

TABLE 3 SEQ SEQ siRNA Target site ID ID No. base positions Sense (5′→3′)NO Anti-sense (5′→3′)  NO (a) 1285~1305 CCGAGAAGCGGUACCUGAACC  2UUCAGGUACCGCUUCUCGGAG  3 (b) 1298~1318 CCUGAACCCGUGUUGCUCUCC  4AGAGCAACACGGGUUCAGGUA  5 (c) 1398~1418 CCUGGCGAUACCUCAGCAACC  6UUGCUGAGGUAUCGCCAGGAA  7 (d) 1434~1454 GCGACUCGCCAGAGUGGUUAU  8AACCACUCUGGCGAGUCGCUG  9 (e) 1435~1455 CGACUCGCCAGAGUGGUUAUC 10UAACCACUCUGGCGAGUCGCU 11 (f) 1436~1456 GACUCGCCAGAGUGGUUAUCU 12AUAACCACUCUGGCGAGUCGC 13 (g) 1438~1458 CUCGCCAGAGUGGUUAUCUUU 14AGAUAACCACUCUGGCGAGUC 15 (h) 1440~1460 CGCCAGAGUGGUUAUCUUUUG 16AAAGAUAACCACUCUGGCGAG 17 (i) 1441~1461 GCCAGAGUGGUUAUCUUUUGA 18AAAAGAUAACCACUCUGGCGA 19 (j) 1443~1463 CAGAGUGGUUAUCUUUUGAUG 20UCAAAAGAUAACCACUCUGGC 21 (k) 1548~1568 GGGAUAACACACUGCAAGUGG 22ACUUGCAGUGUGUUAUCCCUG 23 (l) 1557~1577 CACUGCAAGUGGACAUCAACG 24UUGAUGUCCACUUGCAGUGUG 25 (s) 1557~1579 CACACUGCAAGUGGACAUCAACG 54CGUUGAUGUCCACUUGCAGUGUG 55 (m) 1608~1628 CCACCAUUCAUGGCAUGAACC 26UUCAUGCCAUGAAUGGUGGCC 27 (n) 1700~1720 GCCCUGGACACCAACUAUUGC 28AAUAGUUGGUGUCCAGGGCUC 29 (o) 1706~1726 GACACCAACUAUUGCUUCAGC 30UGAAGCAAUAGUUGGUGUCCA 31 (p) 1778~1798 GACCUCGGCUGGAAGUGGAUC 32UCCACUUCCAGCCGAGGUCCU 33 (q) 1806~1826 CCAAGGGCUACCAUGCCAACU 34UUGGCAUGGUAGCCCUUGGGC 35 (r) 1887~1907 CCCUGUACAACCAGCAUAACC 36UUAUGCUGGUUGUACAGGGCC 37

Example 2 Evaluation of Inhibitory Effect on TGF-β1 Expression (InVitro) (1) Cell

Human alveolar epithelium-derived A549 cells (DS Pharma Biomedical Co.,Ltd.) were used.

(2) Culture Conditions

Using Dulbecco's modified Eagle's Medium (D-MEM) containing 10% fetalbovine serum (with 100 unit/mL penicillin and 100 μg/mL streptomycin),1×10⁵ cells were seeded in a 12-well plate. After culturing under theconditions of 37° C. and 5% CO₂ overnight, the A549 cells were 40%confluent, and the medium was replaced with a serum-free medium.

(3) Pre-Treatment and the Addition Amount of siRNA

As siRNA, oligonucleotides shown in Table 3 above were used, and whenthe cells reached 40% confluence, the oligonucleotides were introducedinto the aforementioned cells using Lipofectamine 2000 (Invitrogen).

Specifically, 2.0 μL of Lipofectamine 2000 was added to 98 μL ofOPTI-MEM (Invitrogen) per well, and the resulting mixture was incubatedat room temperature for five minutes (solution A).

To 99.375 μL of OPTI-MEM, 0.625 μL of a 0.2 μM siRNA solution was added(solution B). Solutions A and B were mixed and incubated at roomtemperature for 20 minutes. After incubation, the AB mixture was addedto each well of the 12-well plate. The siRNA was added so that the finalconcentration was 0.1 nM.

(4) Post-Treatment (i) Cytokine Treatment

Six hours after addition of the mixed solution of siRNA andLipofectamine, the medium was replaced with D-MEM medium containing 0.1%bovine serum albumin (BSA) and cytokine (1 ng/mL IL-1β and 1 ng/mLTNF-α), followed by culturing for 12 hours. After culturing, the culturesupernatants were sampled.

(ii) Extraction of Total Cellular RNA

For extraction of total cellular RNA, an automated nucleic acidextraction apparatus QuickGene-810 (Fujifilm Corporation) and QuickGeneRNA cultured cell kit S (Fujifilm Corporation), which was an exclusivekit for QuickGene-810, were used. The cells were washed with 1.0 mL ofPBS, to which 0.5 mL of a cell lysis solution was added to extract thetotal cellular RNA. After addition of 0.5 mL of the lysis solution (LRC,mercapto ethanol was already added) to the 12-well plate, the plate wasstirred on a see-saw shaker for five minutes. The solution was mixedwell by pipetting five to six times, and then transferred to anEppendorf tube. To the Eppendorf tube, 420 μL of ethanol was added, andthe resulting mixture was stirred on a vortex mixer for 15 seconds andthen processed in QuickGene-810. During processing in QuickGene-810,DNase (RQ1 RNase-free DNase, Promega Corporation) was added. The samplesof the total RNA thus extracted were stored in a refrigerator at −80° C.until the subsequent processing.

(iii) Conversion of the Total RNA into cDNA

The RNA concentrations (μg/mL) in the samples of the total RNA extractedfrom the cultured cells were calculated from the absorption valuemeasured at 260 nm (control: TE buffer). Based on the values thusobtained, the solution of each sample was placed in a 96-well plate insuch an amount that the amount of RNA was 0.1 μg. To each well,distilled water was added to bring the total volume to 12 μL, andfurther, 2 μL of gDNA Wipeout Buffer included in the QuantiTect ReverseTranscription Kit (QIAGEN) was added. After mixing with a vortex, thesamples were incubated at 42° C. for two minutes, and then cooled at 4°C. To these samples, 1 μL of Quantiscript Reverse Transcriptase, 4 μL ofQuantiscript RT Buffer, and 1 μL of RT Primer Mix included in theQuantiTect Reverse Transcription Kit (QIAGEN) were added, followed bymixing and incubation at 42° C. for 15 minutes. Subsequently, thesamples were heated at 95° C. for three minutes to inactivateQuantiscript Reverse Transcriptase, and then cooled at 4° C.

The solution thus prepared (i.e., an undiluted cDNA preparationsolution) was diluted 5-fold with a TE buffer and served as a cDNAsolution for PCR targeting the target gene (TGF-β1).

Also, the undiluted cDNA preparation solution was diluted 50-fold with aTE buffer and served as a cDNA solution for PCR targeting GAPDH, whichwas selected as an internal reference gene. It should be noted that anundiluted cDNA preparation solution of a control sample (i.e., non-siRNAadministration) was diluted 1-, 10-, 100-, and 1000-fold with a TEbuffer and served as a sample to construct a calibration curve for PCRtargeting TGF-β1. Likewise, the undiluted cDNA preparation solution of acontrol sample was diluted 10-, 100-, 1000-, and 10000-fold with a TEbuffer and served as a sample to construct a calibration curve for PCRtargeting GAPDH.

(5) Method for Measuring the Expression Level of TGF-β1

To 2.5 μL of a TGF-β1-derived cDNA product, which was used as atemplate, 12.5 μL of QuantiFast SYBR Green PCR Master Mix (QIAGEN) and2.5 μL of QuantiTect Primer Assay (QIAGEN) for human-derived TGF-β1 geneor human-derived GAPDH gene were added. To the solution, sterilizeddistilled water was added to bring the final volume to 25 μL, whereby aPCR reaction solution was prepared. Then, using Applied Biosystems 7500(Life Technologies Japan Ltd.), the solution thus prepared was heated at95° C. for five minutes and then subjected to 40 cycles of PCR, whereone cycle included 1) 95° C. for 10 seconds and 2) 60° C. for 35seconds, followed by gradual cooling from 95° C. to 60° C. The resultingsolution was subjected to thermal dissociation measurement. Based on thethreshold cycle (Ct) value derived from PCR amplification process, therate of amplification of each target gene was corrected based on the Ctvalue of GAPDH gene, and the inhibitory effect on mRNA of a target genewas evaluated. The results thus obtained are shown in FIG. 1 and Table4.

TABLE 4 Rate of inhibition of TGF-β1 mRNA expression siRNA(TGF-β1/GAPDH) No. nM Mean SD a 0.1 24.7 7.6 b 0.1 85 8.9 c 0.1 51.812.3 d 0.1 58.5 6.4 e 0.1 27.5 2.2 f 0.1 52.1 4.1 g 0.1 51.8 7.5 h 0.129.3 8.6 i 0.1 31.5 12.5 j 0.1 40.1 6.9 k 0.1 22.2 6.6 l 0.1 12.2 6.7 s1 50.1 4.3 m 0.1 71.6 10.4 n 0.1 39.7 4.7 o 0.1 11.7 3.1 p 0.1 55.5 4.4q 0.1 51.3 4.4 r 0.1 53.4 7.8

The siRNAs having siRNA numbers of d, p, r, f, c, g, q, j, n, i, h, e,a, k, l, and o were found to have an inhibition efficiency on the TGF-β1expression of 40% or higher even at a concentration of 0.1 nM.Particularly, siRNAs having siRNA numbers of l and o exhibited aninhibition efficiency of 80% or higher even at 0.1 nM. Further, thesesequences exhibited remarkable inhibitory effects also at 0.01 nM.

Example 3 Production of Chimeric siRNA

Based on the siRNA number (l), chimeric siRNA molecules targeting theTGF-β1 gene as shown in Table 5 below were designed and each chimericsiRNA oligonucleotide was chemically synthesized. The resultingoligonucleotides were purified by HPLC before use.

TABLE 5 SEQ SEQ siRNA No. Sense (5′ → 3′) ID NO Anti-sense (5′ → 3′)ID NO (l-C8a) CACUGCAAGUGGAcatcaacg 38 ttgatgUCCACUUGCAGUGUG 39 (l-C7)CACUGCAAGUGGACatcaacg 40 ttgatGUCCACUUGCAGUGUG 41 (l-C6)CACUGCAAGUGGACAtcaacg 42 ttgaUGUCCACUUGCAGUGUG 43 (l-C5)CACUGCAAGUGGACAUcaacg 44 ttgAUGUCCACUUGCAGUGUG 45 (l-C4a)CACUGCAAGUGGACAUCaacg 46 ttGAUGUCCACUUGCAGUGUG 47 (l-C3)CACUGCAAGUGGACAUCAacg 48 tUGAUGUCCACUUGCAGUGUG 49 (l-C2)CACUGCAAGUGGACAUCAAcg 50 UUGAUGUCCACUUGCAGUGUG 25 (l-C1)CACUGCAAGUGGACAUCAACg 51 UUGAUGUCCACUUGCAGUGUG 25 (l-C4b)CACUGCAAGUGGACAUCaacg 46 UUGAUGUCCACUUGCAGUGtg 56In the table, capital letters, small letters, and underlines indicateRNA, DNA, and overhang positions, respectively.

Example 4 Evaluation of Inhibitory Effect on TGF-β1 Expression

Using the oligonucleotides shown in Table 5 (concentration: 10 nM or 0.1nM), the inhibitory effect on the TGF-β1 expression was evaluated by asimilar method to that in Example 2. The results are shown in FIG. 2 andTable 6.

TABLE 6 Rate of inhibition of TGF-β1 mRNA expression siRNA(TGF-β1/GAPDH) No. nM Mean SD l 10 34.9 4.2 l-C8a 10 56.6 13.2 l-C7 1037.5 5.1 l-C6 10 38.8 0.5 l-C5 10 35.1 6.2 l-C4a 10 37.2 8.0 l-C3 1023.0 6.3 l-C2 10 38.4 7.9 l-C1 10 33.0 2.5 l-C4b 0.1 69.9 4.3

Example 5 Synthesis of Phosphate- or Thiophosphate-Bound Chimeric siRNA

Based on the siRNA number (l), phosphate- or thiophosphate-boundchimeric siRNA molecules targeting the TGF-β1 gene as shown in Table 7below were designed and each chimeric siRNA oligonucleotide waschemically synthesized. The resulting oligonucleotides were purified byHPLC before use.

TABLE 7 SEQ SEQ siRNA No. Sense (5′ → 3′) ID NO Anti-sense (5′ → 3′)ID NO (l-CP8a) CACUGCAAGUGGAcatcaacg 38 P-ttgatgUCCACUUGCAGUGUG 39(l-CP7) CACUGCAAGUGGACatcaacg 40 P-ttgatGUCCACUUGCAGUGUG 41 (l-CP6)CACUGCAAGUGGACAtcaacg 42 P-ttgaUGUCCACUUGCAGUGUG 43 (l-CP5)CACUGCAAGUGGACAUcaacg 44 P-ttgAUGUCCACUUGCAGUGUG 45 (l-CP4a)CACUGCAAGUGGACAUCaacg 46 P-ttGAUGUCCACUUGCAGUGUG 47 (l-CP3a)CACUGCAAGUGGACAUCAacg 48 P-tUGAUGUCCACUUGCAGUGUG 49 (l-CP2)CACUGCAAGUGGACAUCAAcg 50 P-UUGAUGUCCACUUGCAGUGUG 25 (l-CP1)CACUGCAAGUGGACAUCAACg 51 P-UUGAUGUCCACUUGCAGUGUG 25 (l-CP)CACUGCAAGUGGACAUCAACG 24 P-UUGAUGUCCACUUGCAGUGUG 25 (l-CP8b)CACUGCAAGUGGAcatcaacg 38 P-UUGAUGUCCACUUGCAGUGtg 56 (l-CP4b)CACUGCAAGUGGACAUCaacg 46 P-UUGAUGUCCACUUGCAGUGtg 56 (l-CPS4b)CACUGCAAGUGGACAUCaacg 46 PS-UUGAUGUCCACUUGCAGUGtg 56 (l-CP3b)CACUGCAAGUGGACAUCAkcg 57 P-UUGAUGUCCACUUGCAGUGtg 56In the table, capital letters, small letters, and underlines indicateRNA, DNA, and overhang positions, respectively. Also, P- and PS-indicate 5′-terminal phosphorylation and 5′-terminalthiophosphorylation, respectively.

Example 6 Evaluation of Inhibitory Effect on TGF-β1 Expression

Using the oligonucleotides shown in Table 7, the inhibitory effect onthe TGF-β1 expression was evaluated by a similar method to that inExample 2. The results are shown in FIG. 3 and Table 8.

TABLE 8 Rate of inhibition of TGF-β1 mRNA expression siRNA(TGF-β1/GAPDH) No. nM Mean SD l-CP8a 0.1 72.0 3.8 l-CP7 0.1 56.1 2.7l-CP6 0.1 48.2 0.4 l-CP5 0.1 49.4 3.4 l-CP4a 0.1 45.1 3.6 l-CP3a 0.130.6 18.2 l-CP2 0.1 43.1 6.1 l-CP1 0.1 36.1 2.0 l-CP 0.1 44.9 2.0 l-CP8b0.1 57.1 12.4 l-CP4b 0.1 46.4 17.4 l-CPS4b 0.1 70.8 2.2 l-CP3b 0.1 42.12.9

Example 7 Synthesis of siRNA Having DNA in its Overhang Portion

Based on the siRNA number (l), siRNA molecules having DNA in theoverhang portion and targeting the TGF-β1 gene as shown in Table 9 belowwere designed and each siRNA oligonucleotide was chemically synthesized.The resulting oligonucleotides were purified by HPLC before use.

TABLE 9 SEQ SEQ ID ID siRNA No. Sense (5′ → 3′) NO Antisense (5′ → 3′)NO l-0Ha1 CACUGCAAGUGGACAUCAACGt 58 UUGAUGUCCACUUGCAGUGUG 25 l-0Ha2CACUGCAAGUGGACAUCAACGtt 59 UUGAUGUCCACUUGCAGUGUG 25 l-0Ha3CACUGCAAGUGGACAUCAACGttt 60 UUGAUGUCCACUUGCAGUGUG 25 l-0Ha4CACUGCAAGUGGACAUCAACGtttt 61 UUGAUGUCCACUUGCAGUGUG 25 l-0Ha5CACUGCAAGUGGACAUCAACGttttt 62 UUGAUGUCCACUUGCAGUGUG 25 l-0Ha6CACUGCAAGUGGACAUCAACGtttttt 63 UUGAUGUCCACUUGCAGUGUG 25 l-0Ha7CACUGCAAGUGGACAUCAACGttttttt 64 UUGAUGUCCACUUGCAGUGUG 25 l-0Hb1CACUGCAAGUGGACAUCAACGta 65 UUGAUGUCCACUUGCAGUGUG 25 l-0Hb2CACUGCAAGUGGACAUCAACGttaa 66 UUGAUGUCCACUUGCAGUGUG 25 l-0Hb3CACUGCAAGUGGACAUCAACGtttaaa 67 UUGAUGUCCACUUGCAGUGUG 25 l-0Hb4CACUGCAAGUGGACAUCAACGttttaaaa 68 UUGAUGUCCACUUGCAGUGUG 25 l-0Hb5CACUGCAAGUGGAcatcaacgttaa 69 ttgatgUCCACUUGCAGUGUG 39 l-0Hb6CACUGCAAGUGGAcatcaacgtttaaa 70 ttgatgUCCACUUGCAGUGUG 39In the table, capital letters, small letters, and underlines indicateRNA, DNA, and overhang positions, respectively.

Example 8 Evaluation of Inhibitory Effect on TGF-β1 Expression

Using the oligonucleotides shown in Table 9, the inhibitory effect onthe TGF-β1 expression was evaluated by a similar method to that inExample 2. The results are shown in Table 10.

TABLE 10 Rate of inhibition of TGF-β1 mRNA expression siRNA(TGF-β1/GAPDH) No. nM Mean SD l-0Ha1 0.1 26.0 1.0 l-0Ha2 0.1 34.0 6.2l-0Ha3 0.1 32.8 3.8 l-0Ha4 0.1 25.4 1.9 l-0Ha5 0.1 27.4 1.5 l-0Ha6 0.140.1 6.2 l-0Ha7 1.0 39.7 22.6 l-0Hb1 1 24.9 1.7 l-0Hb2 1 25.6 0.9 l-0Hb31 22.8 3.5 l-0Hb4 1 20.4 1.5 l-0Hb5 1 48.6 7.6 l-0Hb6 1 46.6 6.7

Example 9 Evaluation of Efficacy in a Pulmonary Fibrosis Model (In VivoStudy)

Based on the siRNA number (q) (SEQ ID NOs: 34 and 35), which is asequence shared between mice and humans, chimeric siRNA (q-C8: sensestrand (5′→3′): CCAAGGGCUACCAtgccaact (SEQ ID NO: 52), antisense strand(5′→3′): ttggcaUGGUAGCCCUUGGGC (SEQ ID NO: 53) were designed, and in asimilar manner to that in Example 3, chimeric siRNA oligonucleotideswere synthesized and then purified by HPLC. Using the resulting chimericsiRNA oligonucleotides as test substances, efficacy in a mouse model ofbleomycin-induced pulmonary fibrosis was evaluated.

After intraperitoneal administration of pentobarbital (the product ofDainippon Sumitomo Pharma Co., Ltd.) to mice (C57BL/6NCrSlc (SLC),female, 13-week-old), ALZET™ osmotic pumps (model 2001, DURECTCorporation) were implanted under the back skin of the mice underanesthesia to produce pulmonary fibrosis model mice. It is to be notedthat 200 μL of an approximately 10 mg/mL solution of bleomycin inphysiological saline was infused into the ALZET™ osmotic pump inadvance, and for bleomycin, the product of Nippon Kayaku Co., Ltd. wasused.

Three, seven, and 14 days after implantation of the ALZET™ osmotic pump,the test substances were dissolved in distilled water (the product ofOtsuka Pharmaceutical Co., Ltd.) and intratracheally administered usingMicroSprayer™ (model IA-1C, Penn-Century, Inc.) at a dose of 100μg/body. The dose volumes were 75 μL/body on days 3 and 7, and 50μL/body on day 14 after initiation of the bleomycin administration.

Also, as the comparative control, a group in which 200 μL of onlyphysiological saline was infused into the ALZET™ osmotic pump anddistilled water was administered as a test substance, and a group inwhich 200 μL of an approximately 10 mg/mL solution of bleomycin inphysiological saline was infused into the ALZET™ osmotic pump anddistilled water was administered as a test substance were prepared.

Twenty one days after implantation of the ALZET™ osmotic pump,pentobarbital was intraperitoneally administered to the mice, and underanesthesia, the skin and muscle of the neck were removed to expose thetrachea. The mice were sacrificed by exsanguination via the jugularvein, and subsequently, using an indwelling needle, 2 mL ofphysiological saline (Otsuka Pharmaceutical Co., Ltd.) was infused intothe trachea in three divided doses, and approximately 2 mL ofbronchoalveolar lavage fluid (BALF) was collected. Subsequently, thechest was cut open and an incision was made in the left auricle, andapproximately 1 mL of physiological saline was perfused from the rightventricle, and the lungs were excised. For histological evaluation, theleft lobe of the excised lungs was immersed in a 10% formalin neutralbuffer fixation solution (Wako Pure Chemical Industries, Ltd.).

The BALF thus collected was centrifuged (2000 rpm, 4° C., for 10minutes), and the amount of TGF-β1 protein in the supernatant wasmeasured by ELISA. The results are shown in FIG. 4. In the FIG. 4, SAL,DW, and BLM represent saline, distilled water, and bleomycin,respectively.

The lung tissue fixed with a 10% formalin neutral buffer fixationsolution was embedded in paraffin and tissue sections were prepared,which were subjected to Hematoxilin-Eosin (H.E.) staining and Masson'strichrome staining. The tissue diagram is shown in FIG. 5.

From FIG. 4, in the test substance-administration group (BLM/TGF-β1),the amount of TGF-β1 in BALF was found to be remarkably decreased. Thiseffect was not observed in the distilled water-administration group(BLM/DW) as a comparative control. Also, from the tissue diagram of FIG.5, it was found that the degrees of inflammation and fibril formationwere reduced in the test substance-administration group.

1. (canceled)
 2. An siRNA having a full length of 23 or fewernucleotides and selected from the group consisting of an siRNAcomprising a sense sequence of SEQ ID NO: 4 and an antisense sequence ofSEQ ID NO: 5; an siRNA comprising a sense sequence of SEQ ID NO: 10 andan antisense sequence of SEQ ID NO: 11; an siRNA comprising a sensesequence of SEQ ID NO: 12 and an antisense sequence of SEQ ID NO: 13; ansiRNA comprising a sense sequence of SEQ ID NO: 14 and an antisensesequence of SEQ ID NO: 15; an siRNA comprising a sense sequence of SEQID NO: 16 and an antisense sequence of SEQ ID NO: 17; an siRNAcomprising a sense sequence of SEQ ID NO: 18 and an antisense sequenceof SEQ ID NO: 19; an siRNA comprising a sense sequence of SEQ ID NO: 20and an antisense sequence of SEQ ID NO: 21; an siRNA comprising a sensesequence of SEQ ID NO: 22 and an antisense sequence of SEQ ID NO: 23; ansiRNA comprising a sense sequence of SEQ ID NO: 26 and an antisensesequence of SEQ ID NO: 27; an siRNA comprising a sense sequence of SEQID NO: 28 and an antisense sequence of SEQ ID NO: 29; an siRNAcomprising a sense sequence of SEQ ID NO: 30 and an antisense sequenceof SEQ ID NO: 31; an siRNA comprising a sense sequence of SEQ ID NO: 32and an antisense sequence of SEQ ID NO: 33; and an siRNA comprising asense sequence of SEQ ID NO: 36 and an antisense sequence of SEQ ID NO:37.
 3. The siRNA according to claim 2, wherein 1 to 10 consecutivenucleotides excluding an overhang nucleotide from a 3′ terminus of asense strand of the siRNA are converted into DNA.
 4. The siRNA accordingto claim 2, wherein 1 to 10 consecutive nucleotides from a 5′ terminusof an antisense strand of the siRNA are converted into DNA.
 5. The siRNAaccording to claim 2, wherein 1 to 10 consecutive nucleotides excludingan overhang nucleotide from a 3′ terminus of a sense strand of the siRNAare converted into DNA and 1 to 10 consecutive nucleotides from a 5′terminus of an antisense strand of the siRNA are converted into DNA. 6.The siRNA according to claim 2, wherein a 5′ terminus of an antisensestrand is monophosphorylated.
 7. The siRNA according to claim 2, whereina 5′ terminus of an antisense strand is monothiophosphorylated.
 8. Apharmaceutical composition, comprising the siRNA according to claim 2and a pharmaceutically acceptable carrier or diluent.
 9. A method forinhibiting TGF-β1 gene expression, the method comprising: administeringan effective amount of the siRNA according to claim 2 to a human oranimal in need thereof.
 10. A method for preventing or treatingfibrosis, the method comprising: administering an effective amount ofthe siRNA according to claim 2 to a human or animal in need thereof. 11.A method for preventing or treating pulmonary fibrosis or lung cancer,the method comprising: administering an effective amount of the siRNAaccording to claim 2 to a human or animal in need thereof.
 12. A methodfor producing a TGF-b1 gene expression inhibitor, the method comprising:expressing the siRNA according to claim
 2. 13. The siRNA according toclaim 2, wherein all or a part of a 3′ overhang of a sense strand isconverted into DNA.
 14. The siRNA according to claim 13, wherein 1 to 10consecutive nucleotides excluding an overhang nucleotide from a 3′terminus of a sense strand of the siRNA are converted into DNA and 1 to10 consecutive nucleotides from a 5′ terminus of an antisense strand ofthe siRNA are converted into DNA.
 15. An siRNA having a full length of23 or fewer nucleotides and targeting a sequence of 17 to 23 consecutivebases selected from the group consisting of positions 1434 to 1463 ofSEQ ID NO: 1, positions 1548 to 1579 of SEQ ID NO: 1, positions 1608 to1628 of SEQ ID NO: 1, positions 1700 to 1726 of SEQ ID NO: 1, positions1778 to 1798 of SEQ ID NO: 1, and positions 1887 to 1907 of SEQ ID NO:1.